Taking tissue samples from various parts of the digestive system is often required for analysis. One such system is a bile duct (biliary) system. The biliary system delivers bile produced by the liver to the duodenum where the bile assists other gastric fluids in digesting food. The biliary system includes the liver, as well as a plurality of bodily channels and organs that are disposed between the liver and the duodenum. When the liver produces the bile, the bile enters biliary ducts, having relatively small cross-sectional areas, that are dispersed throughout the liver. These biliary ducts carry the bile away from the liver and gradually merge with other biliary ducts to form larger biliary ducts. The last of the biliary ducts merge into the main biliary duct, from which the bile flows into the duodenum.
The biliary system also includes a gall bladder connected to one or more of the biliary ducts via the cystic duct. The gall bladder stores excess bile produced by the liver and introduces the stored bile into the duodenum via the cystic duct and the biliary ducts when necessary.
Sometimes, however, lesions may grow in portions of the biliary system, for example, one of the biliary ducts, that impede bile from properly flowing through the system. In some cases, the lesions may completely prevent the bile flow. This is undesirable as it interrupts the regular digestive process and may even cause damage to the channels and organs of the biliary system.
In order to properly treat the lesions, it is sometimes necessary to acquire a sample from the lesion, analyze the sample, and then determine a proper treatment based on the analysis. The sample may be acquired by advancing a cytology brush through the gastrointestinal tract to the duodenum, into the biliary system via the main biliary duct, and then up through the bile ducts to the lesion. The cytology brush may then be advanced against the lesion to collect cells for analysis. Certain drawbacks of cytology brushes may include difficulty in steering the brush to the correct location, determining whether the lesion has been brushed, and obtaining sufficient samples for analysis.